Composition and process for the removal of asphaltenic containing organic deposits from surfaces

ABSTRACT

Removal of organic deposits from surfaces, particularly those deposits containing asphaltenic compounds, by the dissolution of the deposits in a solvent comprised of an aromatic hydrocarbon and an amine.

United States Patent 1191 Sutton Oct. 21, 1975 1 COMPOSITION AND PROCESS FOR THE [56] References Cited REMOVAL OF ASPHALTENIC UNITED STATES PATENTS CONTAIMNG ORGANIC DEPOSITS FROM 1,643,675 9/1927 Montgomerie 252/3115 SURFACES y 2,509,197 5/1950 Borus et a1 252/153 X [75] Inventor: Gary D. Sutton, Duncan, Okla. Egg et a] g 7 Assignee; Halliburton Company, Duncan Dykstra 252/153 X Okla 3,137,730 6/1964 Fitz'William.,.. 260/583 P x 1 3,279,541 10/1966 Knox et a1 252/855 B X [22] May 1973 OTHER PUBLICATIONS [21] APPL N05 3591946 Jeffries-Harris at I a1. Solvent Stimulation in Low [44] Published under the Trial Voluntary Protest Gravity Resrvoirs Journal of Petroleum Tech Program on January 28, 1975 as document no. nology, February 1969; PP- B P E R b L 1; d J

rimary xaminero ert 1n say, r. Related Appl'cat'on Data Assistant Examiner-M. Steven Alvo [63] Continuation-in-part of Ser. No. 164,449, July 20, Attorney A or Fi Th ma R, Weaver; John 1971, abandoned. H. Tregoning [52] US. Cl 134/40; 106/278; 134/22'R; 57 ABSTRACT 252/855 B; 252/153; 252/364; 252/544 R l f d f f 51 Int. Cl. C23G 5/02 I L i t [58] Field of Search 106/278; 260/583 P; 13 ggzgf gf gg"zfi iz g f fg;

252/154, 153, 544, 364, 8.55 B; 134/22 c, P 2 Y f h d d 22 R, 40 2 comprised 0 an aromatic y rocar on an an amine.

17 Claims, N0 Drawings COMPOSITION AND PROCESS FOR THE REMOVAL OF ASPHALTENIC CONTAINING ORGANIC DEPOSITS FROM SURFACES This is a continuation-in-part of parent application Ser. No. 164,449 filed July 20, 1971 now abandoned. The entire disclosure of said parent application is hereby incorporated herein by reference.

The present invention relates to the removal of organic deposits from surfaces, and more particularly, but not by'way of limitation, to a method and solvent for removing organic deposits containing asphaltenic compounds from surfaces.

Organic deposits derived from crude oil have long been a source of trouble and operating expense to petroleum producers. These organic deposits may be almost totally paraffinic in nature or they may be highly asphaltic, depending on the particular crude oil produced. The deposits accumulate in tubular goods, production and storage equipment, and pipelines, as well as on the faces of producing formations in oil and water wells. As the organic deposits build up in production equipment, tubular goods, and related apparatus, production is gradually decreased until remedial work is required to remove the deposits. Heretofore, removal of such organic deposits has been accomplished by mechanical scraping of the surfaces of equipment utilizing knives, scrapers, and similar devices, and also by dissolving the deposits in solvents such as hot crude oil and kerosene. One method involving the application of a hot solvent to the deposit to effect the removal of the deposit is disclosed by Knox et al. in U.S. Pat. No. 3,279,541. Knox et al. discloses combining a heat generating chemical with an aqueous solution to provide the heat source, adding thereto a light paraffin solvent to become heated, and contacting the deposit to be removed with the thus heated solvent.

While solvents such as hot crude oil and kerosene are relatively effective for dissolving organic deposits which are paraffinic in nature, they are relatively ineffective for dissolving asphaltenic compounds. In general, organic deposits of high asphaltenic compound content are hard and brittle while deposits formed primarily of paraffinic compounds are soft and pliable. Thus, deposits containing asphaltenic compounds have heretofore been particularly troublesome to oil producers in that they are difficult to remove by mechanical methods and conventional solvents are relatively ineffective in their removal. Stripping asphaltenes from mineral surfaces is discussed in an article by Jeffries- Harris et al. entitled Solvent Stimulation in Low Gravity Oil Reservoirs which appears in the February 1969 issue of the Journal of Petroleum Technology at page l7l. The author discloses the use of a standard well stimulation solvent, diesel oil, by itself and in combination with certain additives to dissolve asphaltenes. Some of the materials utilized by J effries-Harris include diesel oil; diesel oil-% xylene; diesel oil-5% xylene-l% n-butyl amine; diesel oil-1% n-butylamine; diesel oil- 5% toluene; and diesel oilhexylamine. The combination of diesel oil and 1% n-butylamine appeared to be substantially superior to diesel oil alone with respect to dissolving asphaltenes, but the combinations diesel oil-5% xylene-1% n-butylamine, diesel oil-5% xylene, and diesel oil-5% toluene appeared to provide very little, if any, improvement to the solvent power of diesel oil.

wherein R, R, and R represent members selected from the group consisting of hydrogen, alkyl radicals having from 1 to 4 carbon atoms, alkylamine radicals having from 1 to 4 carbon atoms, cycloalkyl radicals having from 3 to 6 carbon atoms and mixtures thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is directed to a method and solvent for dissolving organic deposits containing asphaltenic compounds. Broadly described, the solvent of the present invention comprises a liquid aromatic hydrocarbon having an amine combined therewith selected from the group consisting of pyridine, morpholine and primary, secondary, and tertiary amines defined by the following general formula:

wherein R, R, and R" represent members selected from the group consisting of hydrogen, alkyl radicals having from 1 to 4 carbon atoms, alkylamine radicals having from I to 4 carbon atoms, cycloalkyl radicals having from 3 to 6 carbon atoms and mixtures thereof.

Compounds defined by the above formula which are preferred for use herein have no more than two nitrogen atoms per molecule. Compounds which are within the scope of the above formula having more than one nitrogen atom per molecule do not feature direct nitrogen to nitrogen bonding.

It has been found that the solvent of this invention, which is comprised of an aromatic hydrocarbon and an amine, in particular amounts of each, unexpectedly dissolves a greater quantity of organic deposits containing asphaltenic compounds in the same interval of time than would be predicted from either the amine or the aromatic hydrocarbon acting alone.

A preferred solvent of the present invention consists essentially of a liquid aromatic hydrocarbon and an amine of the type described above wherein the amine is present in the solvent in an amount of from about 1 to about 50 and more preferably about 1 to about 35 percent by total volume of solvent.

Examples of aromatic hydrocarbons which are particularly useful in the present invention are benzene, toluene and xylene. Examples of amines which are par ticularly useful in the present invention are pyridine,

3 morpholine, and low molecular weight primary, secondary, and tertiary amines such as n-butylamine, ethylenediamine, diethylenetriamine, dimethylaminopropylamine, diethylaminopropylamine, and cycloalkyl amines such as cyclohexylamine.

A more specific preferred solvent of the present invention is comprised of an aromatic hydrocarbon selected from the group consisting of benzene, toluene and xylene and an amine selected from the group consisting of n-butylamine, ethylenediamine, diethylenetriamine, and dimethylaminopropylamine, wherein the amine is present in the solvent in an amount of from about 3 to about percent by total volume of solvent.

Yet a more specific preferred solvent of the present invention consists essentially of xylene and ethylenediamine wherein the ethylenediamine is present in the solvent in an amount of about 5 percent by total volume of solvent.

1n the process for the removal of organic deposits containing asphaltenic compounds from surfaces, the solvent of this invention can be circulated over the surface from which the deposit is to be removed or the solvent can be allowed to contact the deposit to be re moved in a static condition for a period of time sufficient for the scale to be removed. The contacting can proceed at normal temperatures or the solvent can be heated at the discretion of the user. The solvents of the present invention dissolve organic deposits containing asphaltenic compounds and once the deposit has been dissolved and the solvent removed, no further treatment is necessary.

The following examples are provided to exhibit certain specific embodiments of the solvent and process of this invention. However, these embodiments are presented by way of example and not by way of limitation of the scope of this invention.

In the Examples which follow, the experimental procedure utilized is set out below:

Several standard solutions consisting solely of known quantities of asphaltic material dissolved in xylene are prepared. A sample of each solution is then diluted with reagent grade xylene at the rate of 25 milliliters xylene per 1 milliliter solution.

Thereafter the diluted solutions are examined in a colorimeter apparatus wherein incandescent light is passed through each solution and the quantity of light passing through the solution is measured by the apparatus. The apparatus employed, a Spectronic Colorimeter, is adjusted to measure the quantity of light having a wavelength of 635 millimicrons which passes through a solution. The data recorded is percent transmittance,-

4 i.e. the percent of available 635 millimicron light passing through the solution.

Prior to the measurement of each solution, the colorimeter is checked against reagent grade xylene to assure that the percent transmittance for reagent grade xylene alone is measured by the apparatus as being 0... hundred percent.

The various known xylene-asphaltic solutions and measured transmittances at 635 millimicrons is set out in Table A below:

TABLE A Solution Percent Transmittance grams asphaltic material per milliliter xylene The data in Table A is then plotted on semi-log paper. The resulting curve is then used in subsequent experimentation and is accordingly referred to hereinafter as Curve A.

Individual test solutions of approximately 25 milliliters each are then prepared by mixing a known quantity of an amine with a known quantity of xylene. lnto each test solution, the temperature of which is about F, there is then placed a piece of asphaltic material. The asphaltic material utilized is taken from a common source, and the initial surface area of the asphaltic material added to each test solution is approximately the same.

The asphaltic material is maintained in the test solution for a fixed period of time at the termination of which the solution is filtered to remove all undissolved material. A sample of filtrate from each test solution is then collected and diluted with 25 milliliters reagent grade xylene per 1 milliliter of test solution. The diluted test solutions are then subjected to colorimetric analysis exactly as described above.

The percent transmittance for each test solution is recorded, and the recorded transmittance is then used with Curve A to determine the quantity of asphaltic material dissolved by the solution.

Table B, below sets out the dissolution properties of n-butylamine-xylene and ethylenediamine-xylene for asphalt, wherein the contact time for n-butylaminexylene and asphalt is 10 minutes and the contact time for ethylenediamine-xylene and asphalt is 5 minutes.

TABLE B Solvent, by Volume Specific Transgrams asphalt Gravity mittance per milliliter of Solvent Percent solvent in amine Xylene gms/ml at 635 mu -minutes X 10 n-butylamine 10 minutes 0 100 0.860 93 3.0 1 99 0.86 6.2 3 97 0.86 36 50.7 5 95 0.858 36 50.7 10 0.850 49 31.2 20 80 0.840 19 90.0 50 50 0.802 62 7.8 100 0 0.764 96 1.8 ethylenediamine 5 minutes TABLE B-continued Solvent, by Volume Specific Transgrams asphalt Gravity mittance per milliliter of Solvent Percent solvent in amine Xylene gms/ml at '635 mu -minutes X l0" From Table B, above, it is clearly seen that the amine-xylene solvents of this invention dissolve much greater quantities of asphalt per milliliter of solvent in the same period of time than could reasonably be predicted from the asphalt dissolving properties of the individual constituents when acting alone. A plot of the columns Solvent, by Volume, versus gms asphalt per milliliter solvent in minutes still more clearly illustrates the unexpected results achieved by the solvent of this invention.

In order to still further compare the solvent of this invention with solvents of the prior art, two solvents disclosed in the previously mentioned article by Jeffries- Harris et al. are prepared as follows:

Prior Art Solvent A by Prior Art Solvent B by Ingredient Volume of Solvent Volume of Solvent Kerosine 99 94 n-butylamine l l xylene 0 5 EXAMPLE 1 Asphaltene solubility tests in various solvents of the present invention are given in Table I below. The relative solvent improvement is based on solubility in pure xylene as compared with solubility in xylene combined with the amine given in the table at an amine concentration of 5 percent by volume. The solubility test procedure utilized is as previously described. After 5 minutes, each solvent is gently swirled and filtered. The filtrates from each sample are then analyzed by the colorimetric procedure described above to determine the solubility of the deposits therein. The relative solvent improvement is then the ratio of asphalt dissolved by the solvent herein to the asphalt dissolved by xylene alone.

TABLE I COMPARISON OF ASPHALTENE* DISSOLUTION IN 5 MINUTES FOR XYLENEAMINE MIXTURES AT AMINE CONCENTRATIONS OF 5% BY VOLUME Relative Solvent Improvement TABLE I-continued COMPARISON OF ASPHALTENE* DISSOLUTION IN 5 MINUTES FOR XYLENE-AMINE MIXTURES AT AMINE CONCENTRATIONS OF 5% BY VOLUME Relative Solvent Improvement Amine As Compared to Xylene Alone Ethylenediamine l 1.45

*Organic deposits containing asphaltenic compound used herein were removed from metal surfaces in contact with crude oil produced from 5050 Field. Mississippi. The organic deposits tested herein had the following analysis: asphaltene 631%. paraffin 1.5%. entrapped oil and pentane solubles 35.4%.

From the above data it may be seen that a considerable relative solvent improvement in 5 minutes is obtained using the solvents of the present invention. Since the amines and xylene alone are relatively poor solvents for asphaltenic compounds, a synergistic effect or result is produced by the solvents of the present invention.

EXAMPLE 2 A solvent comprised of xylene and 1 percent by volume n-butylamine is prepared. The solubility therein of organic deposits containing asphaltenic compounds is determined and compared with the solubility of the same deposits in xylene alone. The xylene-amine solvent dissolves the deposits 2.06 times as well in 10 minutes as the xylene alone.

EXAMPLE 3 A solvent comprised of xylene and n-butylamine wherein the n-butylamine is present in the amount of 10 percent by volume is prepared. The solubility of organic deposits containing asphaltenic compounds in the solvent is determined and compared with the solubility of the deposits in xylene alone. It is found that the xylene-amine solvent dissolves the deposits 10.4 times as well in 10 minutes as the xylene alone.

EXAMPLE 4 EXAMPLE 5 A solvent comprised of xylene and n-butylamine is prepared wherein the n-butylamine is present in an amount of 20 percent by volume. The solubility of organic deposits containing asphaltenic compounds in the solvent is determined and compared with the solubility of the same deposits in xylene alone. It is found 7 that the xylene-amine solvent dissolves the deposits 30.0 times as well in 10 minutes as the xylene alone.

EXAMPLE 6 A solvent comprised of xylene and n-butylamine is prepared wherein the n-butylamine is present in an amount of percent by volume. The solubility of organic deposits containing asphaltenic compounds in the solvent is determined and compared with the solubility of the same deposits in xylene alone. It is found that the xylene-amine solvent dissolves the deposits 16.9 times as well in minutes as the xylene alone.

The present invention, therefore, is well adapted to attain the ends and advantages mentioned as well as those inherent therein. The foregoing disclosure and description is illustrative and explanatory of the invention and suitable variations may be made by those skilled in the art which are deemed to be circumscribed by the spirit and scope of the invention except as necessarily limited by the appended claims or reasonable equivalents thereof.

What is claimed is:

1. A method for removing organic deposits containing asphaltenic compounds from surfaces which comprises contacting said deposits with a solvent consisting essentially of a hydrocarbon selected from the group consisting of benzene, toluene, and xylene and an amine selected from the group consisting of pyridine, morpholine, and primary, secondary and tertiary amines represented by the formula wherein R, R, and R" are selected from the group consisting of hydrogen, alkyl radicals having from 1 to 4 carbon atoms, alkyl amine radicals having from 1 to 4 carbon atoms, cycloalkyl radicals having from 3 to 6 carbon atoms and mixtures thereof and, further, wherein said amine is present in said solution in an amount of from about 1 percent to about 50 percent by volume.

2. The method of claim 1 wherein said amine is present in an amount of from about 3 percent to about 35 percent by volume.

3. The method of claim 2 wherein said amine is selected from the group consisting of n-butylamine, ethylenediamine, diethylenetriamine, dimethylaminopropylamine, diethylamine, and diethylaminopropylamine.

4. The method of claim 3 wherein said hydrocarbon is xylene.

5. The method of claim 4 wherein said amine is ethylenediamine and is present in an amount of about 5 percent by volume.

6. A method of removing organic deposits containing asphaltenic compounds from within oil production equipment comprising the steps of contacing said deposits within said equipment with a solvent consisting essentially of a hydrocarbon selected from the group consisting of benzene, toluene, and xylene, and an amine selected from the group consisting of pyridine and morpholine, and primary, secondary, and tertiary amines represented by the formula wherein R, R, and R are members of the group cor;

sisting of hydrogen, alkyl radicals having from 1 to 4 carbon atoms, alkyl amine radicals having from 1 to 4 carbon atoms and cycloalkyl radicals having from 3 to 6 carbon atoms and mixtures thereof; and removing said solvent from said equipment after said deposits have been dissolved therein; wherein said amine is present in said solvent in an amount of from about 1 percent to about 35 percent by volume.

7. The method of claim 6 wherein said amine is present in an amount from about 3 percent to about 10 percent by volume.

8. The method ofclaim 7 wherein said amine is selected from the group consisting of n-butylamine, ethylenediamine, diethylenetriamine, dimethylaminopropylamine, diethylamine, and diethylaminopropylamine.

9. The method of claim 8 wherein said hydrocarbon is xylene.

10. The method of claim 9 wherein said amine is ethylenediamine and is present in an amount of about 5 percent by volume.

11. A solvent for asphaltenic-containing compounds, said solvent consisting essentially of a hydrocarbon selected from the group consisting of benzene, toluene, and xylene, and an amine selected from the group consisting of pyridine, diethylaminopropylamine, diethylamine, n-butylamine, dimethylaminopropylamine, ethylenediamine, and diethylenetriamine, wherein said amine is present in an amount of from 1 percent to about 35 percent by volume.

12. The solvent of claim 11 wherein said amine is present in an amount of from about 3 percent to about 10 percent by volume.

13. The solvent of claim 12 wherein said amine is selected from the group consisting of n-butylamine, ethylenediamine, diethylenetriamine, dimethylaminopropylamine, diethylamine, and diethylaminopropylamine.

14. The solvent of claim 13 wherein said hydrocarbon is xylene.

15. The solvent of claim 14 wherein said amine is ethylenediamine present in an amount of about 5 percent by volume.

16. A method for removing organic deposits containing asphaltenic compounds from surfaces which comprises contacting said deposits with a solvent consisting essentially of a hydrocarbon selected from the group consisting of benzene, toluene, and xylene, and an amine represented by the general formula .amount of from about 1 percent to about 35 percent by 3,914,132 9 10 volume. mine, and n-butylamine, and further wherein said 17. The method of claim 16 wherein said hydrocaramine is present in an amount of from about 3 percent bon is xylene and said amine is selected from the group to about 20 percent by volume. consisting of ethylenediamine, dimethylaminopropyla- 5 

1. A METHOD FOR REMOVING ORGANIC DEPOSITS CONTAINING ASPHALTENIC COMPOUNDS FROM SURFACES WHICH COMPRISES CONTACTING SAID DEPOSITS WITH A SOLVENT CONSISTING ESSENTIALLY OF A HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF BENZENE, TOLUENE, AND XYLENE AND AN AMINE SELECTED FROM THE GROUP CONSISTING OF PYRIDINE, MORPHOLINE, AND PRIMARY, SECONDARY AND TERTIARY AMINES REPRESENTED BY THE FORMULA
 2. The method of claim 1 wherein said amine is present in an amount of from about 3 percent to about 35 percent by volume.
 3. The method of claim 2 wherein said amine is selected from the group consisting of n-butylamine, ethylenediamine, diethylenetriamine, dimethylaminopropylamine, diethylamine, and diethylaminopropylamine.
 4. The method of claim 3 wherein said hydrocarbon is xylene.
 5. The method of claim 4 wherein said amine is ethylenediamine and is present in an amount of about 5 percent by volume.
 6. A METHOD OF REMOVING ORGANIC DEPOSITS CONTAINING ASPHALTENIC COMPOUNDS FROM WITHIN OIL PRODUCTION EQUIPMENT COMPRISING THE STEPS OF CONTACTING SAID DEPOSITS WITHIN SAID EQUIPMENT WITH A SOLVENT CONSISTING ESSENTIALLY OF A HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF BENZENE, TOLUENE, AND XYLENE, AND AN AMINE SELECTED FROM THE GROUP CONSISTING OF PYRIDINE AND MORPHOLINE, AND PRIMARY, SECONDARY, AND TERIARY AMINES REPRESENTED BY THE FORMULA
 7. The method of claim 6 wherein said amine is present in an amount from about 3 percent to about 10 percent by volume.
 8. The method of claim 7 wherein said amine is selected from the group consisting of n-butylamine, ethylenediamine, diethylenetriamine, dimethylaminopropylamine, diethylamine, and diethylaminopropylamine.
 9. The method of claim 8 wherein said hydrocarbon is xylene.
 10. The method of claim 9 wherein said amine is ethylenediamine and is present in an amount of about 5 percent by volume.
 11. A SOLVENT FOR ASPHALTENIC-CONTAINING COMPOUNDS, SAID SOLVENT CONSISTING ESSENTIALLY OF A HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF BENZENE, TOLUENE, AND XYLENE, AND AN AMINE SELECTED FROM THE GROUP CONSISTING OF PYRIDINE, DIETHYLAMINOPROPYLAMINE, DIETHYLAMINE, N-BUTYLAMINE, DIMETHYLAMINOPROPYLAMINE, ETHYLENEDIAMINE, AND DIETHLENETRIAMINE, WHEREIN SAID AMINE PRESENT IN AN AMOUNT OF FROM 1 PERCENT TO ABOUT 35 PERCENT BY VOLUME.
 12. The solvent of claim 11 wherein said amine is present in an amount of from about 3 percent to about 10 percent by volume.
 13. The solvent of claim 12 wherein said amine is selected from the group consisting of n-butylamine, ethylenediamine, diethylenetriamine, dimethylaminopropylamine, diethylamine, and diethylaminopropylamine.
 14. The solvent of claim 13 wherein said hydrocarbon is xylene.
 15. The solvent of claim 14 wherein said amine is ethylenediamine present in an amount of about 5 percent by volume.
 16. A METHOD FOR REMOVING ORGANIC DEPOSITS CONTAINING ASPHALTENIC COMPOUNDS FROM SURFACES WHICH COMPRISES CONTACTING SAID DEPOSITS WITH A SOLVENT CONSISTING ESSENTIALLY OF A HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF BENZENE, TOLUENE, AND XYLENE, AND AN AMINE REPRESENTED BY THE GENERAL FORMULA
 17. The method of claim 16 wherein said hydrocarbon is xylene and said amine is selected from the group consisting of ethylenediamine, dimethylaminopropylamine, and n-butylamine, and further wherein said amine is present in an amount of from about 3 percent to about 20 percent by volume. 